Endoscopic Vitrectomy Combined with 3D Heads-Up Viewing System in Treating Traumatic Ocular Injury

Purpose To investigate effects and complications of endoscopic vitrectomy combined with 3D heads-up viewing system in treating traumatic ocular injury. Patients and Methods. This is a retrospective interventional case series in a tertiary referral center in Taiwan, and we included patients of traumatic ocular injury, and they underwent endoscopic vitrectomy combined with a 3D heads-up viewing system. Results Fourteen eyes of traumatic globe injury from 14 patients were studied over a 30-month period. Preoperative VA ranged from no light perception (NLP) to 6/6. Postoperative visual acuity improved in 11 of the 14 eyes (79%). Until 6 months after surgery, all eyes had attached retina. The median logMAR BCVA was 2.4 at the first visit and 1.19 at the last visit (p = 0.0028). No subject suffered from retinal detachment, endophthalmitis, or other severe complications. Conclusions Vitrectomy using endoscopy combined with 3D heads-up viewing system allowed early evaluation and intervention in traumatic ocular injuries. Most of our cases showed both anatomical and visual acuity improvements.


Introduction
Traumatic ocular injury is a common cause of ocular morbidity and permanent visual impairment worldwide [1][2][3][4].It requires urgent treatment because blindness not only afects life quality but also productivity [5].For open globe injuries involving the posterior segment, the sooner surgical intervention is performed, the better the prognosis [6].In the acute stage, vision is often highly compromised due to the concurrent presence of corneal edema, infammatory membranes, or hemorrhage.For eyes with an opaque cornea following ocular trauma, endoscopic surgery allows an earlier diagnosis and prevents retinal pathology such as retinal damage and detachment.
Tree-dimensional (3D) surgery system consists of a high dynamic range camera installed on a microscope with a device for 3D display.Te surgeon who operates it wears a pair of polarized glasses.Two images are merged and then separated horizontally through the polarized glasses so that each eye sees a slightly disparate image, producing depth perception with the two eyes.A 3D surgery system allows the surgeon to perform the procedure in a more comfortable "Heads-Up" position than when looking through the microscope [7,8].It is used in both anterior and posterior ophthalmic surgical procedures.It is considered a safe and ergonomic operation system for ophthalmic surgery [9].
Currently, the 3D heads-up viewing system for vitreoretinal surgery is becoming increasingly popular.However, reports on the combined endoscope and 3D viewing system for vitrectomy are limited.Here, we aim to investigate the efects of vitrectomy with endoscopy combined with the 3D heads-up viewing system in the treatment of traumatic ocular injuries.

Patients and Methods
Tis is a single-site, retrospective case series.We collected clinical data of patients visiting a tertiary referral center in Taiwan, the Taichung Veterans General Hospital, during the period from November 1, 2019, through May 1, 2021.Tis study adhered to the tenets of the Declaration of Helsinki.All patients were clearly informed about the use of endoscope and the 3D surgical system for the operation and related risks.All patients signed the informed consent form on the operation.All patients' information was anonymized prior to analysis.
Te inclusion criteria for this study were patients with traumatic ocular injuries who underwent endoscopic vitrectomy with a 3D head-up system from November 1, 2019 to May 1, 2021.Te exclusion criteria were patients with critical condition requiring life support, clinical follow-up period less than 6 months, preexisting retinal diseases, and age under 18 years old.
Surgical procedures were performed using 23-gauge or 25-gauge three-port pars plana vitrectomy (CONSTELLA-TION Vision System, Alcon Laboratories, Inc.) under a microscope with a noncontact wide-feld visualization system.Specifcally, a NGENUITY 3D visualization system (Alcon Laboratories, Inc.) was attached to a microscope (Carl Zeiss Meditec) for observing all surgical procedures.During the surgery, the surgeon wore a pair of passive 3D polarized glasses and positioned himself about 2 meters away from the screen.Te endoscope system was Endo Optiks E4 (Endo Optiks, Inc., Little Silver, NJ, USA).
Te vitrectomy technique entailed a 23-gauge/25-gauge three-port pars plana approach involving a sclerotomy located 3 to 3.5 mm posterior to the limbus.If the patient had traumatic cataract or lens dislocation, we performed lensectomy with complete removal of the capsular bag but no lens implantation.Core vitrectomy was performed and the peripheral vitreous was carefully shaved using scleral depression.In the case of intraocular foreign body (IOFB), the foreign body was removed by forceps.In the patient of IOL dislocation, suture IOL was performed.Te air-fuid exchange was done in the event of retinal detachment, and the subretinal fuid was drained out.Te subretinal proliferations were extracted from the retinotomy if it was difcult to fatten the retina after air-fuid exchange.Endolaser photocoagulation was applied whenever needed.Silicone oil or gas tamponade was performed at the end of the surgery if necessary.In the patient of proliferative vitreoretinopathy (PVR), encircling scleral buckle was placed.Te representative image is shown in Figure 1.
Statistical analyses were conducted using the Statistical Package for the Social Sciences (IBM SPSS version 22.0; International Business Machines Corp, New York, USA).Snellen or best-corrected visual acuity (BCVA) values were converted into the logarithm of the minimum angle of resolution (logMAR) for statistical analysis.Te following logMAR assignments were used for BCVA worse than 1/200: counting fngers (CF) � 2.0, hand motion (HM) � 2.3, light perception (LP) � 2.7, and no light perception (NLP) � 3. Preoperative and postoperative visual acuities were compared using the Wilcoxon signed-rank test.Te diference in fnal visual acuity between the OTS group and our series was analyzed using the chi-square test.Preoperative visual acuity worse than 1/200 rates was compared with postoperative visual acuity worse than 1/200 rates using the McNemar test.A p value of <0.05 was considered statistically signifcant.
3.1.Anatomical Success.Until 6 months after surgery, all eyes (100%) showed attached retina.Most retinae were reattached without tamponade.During the initial surgery, 6 eyes were flled with silicone oil and 2 eyes were flled with SF6 gas.Silicone oil was removed in 3 eyes and the remaining 3 eyes was flled with silicone oil until the last follow-up visit.

Visual Acuity and OTS.
Te median logMAR BCVA was 2.4 at the frst visit and 1.19 at the last visit (p � 0.0028, by the Wilcoxon signed-rank test).A total of 11 cases (79%) had visual acuity less than 1/200 on presentation.After calculating the ocular trauma score (OTS), patients were categorized in group 1 of 8 eyes and group 2 of 6 eyes.Improvements in postoperative visual acuity were found with 11 of the 14 eyes (79%) (Table 2).Two eyes still showed good visual acuity (6/6) after 6 months.Tere was one eye initially sufered from open globe injury, retinal detachment, and submacular hemorrhage.Te retina was reattached after treatment, but the vision remains poor with light perception due to optic atrophy.Final VA distributions based on OTS categories are presented in Table 3. Tere is a signifcant diference in fnal visual acuity between the OTS group and our series, as shown in Table 4.

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Journal of Ophthalmology 3.3.Complications.We found no intraoperative complication, nor postoperative complication like retinal detachment, endophthalmitis, and other severe complications.

Discussion
Te ocular trauma score (OTS) is a system widely used to predict the visual prognosis of patients with traumatic ocular injury.All of the injured eyes included in this study belonged to the more serious and poorer prognosis group (OTS categories 1 and 2).In OTS, only 3% of category 1 patients was predicted to achieve visual acuity 6/60 or greater.However, in our study, 30% of patients achieved visual acuity 6/60.Similarly, 50% of category 2 patients in our study had visual acuity greater than 6/60, compared with 28% predicted by OTS.Te diference was statistically signifcant, as indicated in Table 4. Te reason we think why the visual prognosis of patients in our study is better than that predicted by OTS is that early intervention can improve the prognosis of patients with severe ocular trauma.Te combination of endoscopy and 3D imaging is a powerful tool to provide us with early interventional surgery.
Vitrectomy is a challenging procedure for surgeons on severely injured eyes with corneal opacity.Temporary keratoprosthesis (TKP) is a useful tool for visualizing the retina during vitrectomy.However, implantation of TKP requires more procedures and that prolongs the operation time.Besides, the open-sky stage increases the risk of suprachoroidal hemorrhage.Te intraoperative manipulation and the use of silicone oil are associated with corneal graft failure [11,12].Unlike the conventional viewing system, endoscopy can bypass opaque cornea to give a view of the posterior segment, allowing early intervention and preventing late complications after severe ocular trauma.
Te endoscopic approach ofers signifcant advantages for vitreoretinal surgery for traumatic cases.Because endoscopes can access the retina and intraocular structures closely, they can provide proximal views of structures of interest, including the ciliary body, pars plana, and peripheral retina [13].Besides, the endoscopy obviates   aggressive scleral indentation, which should be preferably avoided for eyes with recent open globe injuries [14].Although vitrectomy under air is often efective in terms of retinal stabilization, visualizing the retina is markedly compromised in certain situations [15].Terefore, the endoscope allows for observation in close proximity to the retina, even under air.Sabti and coworkers reported serial cases of endoscopic-assisted vitrectomy for treating severe ocular trauma.Tey found that among their 50 eyes with open globe injuries, 36 (83.7%) showed improved vision after surgery [16].In our present study, we observed anatomical success in all 14 eyes.Additionally, the number of eyes exhibiting visual acuity worse than 1/200 signifcantly decreased (from 10 eyes to 3 eyes) (McNemar test, p � 0.016).
IOFBs increase the risk vision-threatening complications like endophthalmitis, retinal detachment, and toxic optic neuropathy or retinopathy [17].Immediate removal of IOFBs is important to reduce the risk of endophthalmitis and permanent vision loss [18,19].Endoscopy facilitates IOFB removal by direct visualization of difcult-access structures such as the ciliary body, ciliary sulcus, and peripheral retina.It also provides better surgical feld to conduct complete vitrectomy, which could reduce  pathogenic microorganisms.In the present study, IOFBs were successfully removed in 3 cases.We noted no endophthalmitis with good VA improvements after surgery.Proliferative vitreoretinopathy (PVR) is an independent risk factor of unfavorable outcome for ocular trauma [20].Anterior PVR might cause ciliary body fbrosis that subsequently leads to hypotony and phthisis [21].Te endoscope is an ideal tool for assessing ciliary body status and determining whether or not to perform silicone oil flling [22].Endoscopy is considered important in treating PVRrelated retinal detachment concurrent with severe corneal opacity.Kita and coworkers reported a case series of advanced PVR using the endoscopic approach.Tey found that at the mean follow-up of 8.2 months after frst endoscopic vitrectomy, 3 of 4 subjects (75%) had achieved successful retinal reattachment under silicone oil [23].In our present study, we had one case of chronic trauma with pupil synechia, retinal detachment, and PVR changes (patient no.5).After operation, his retina was attached under silicone oil.His visual acuity also improved from NLP to HM, despite limited improvement due to macular degeneration.
Incomplete removal of residual vitreous could result in complications like vitreous incarceration and retinal detachment [24].Te 3D heads-up visualization system provides a number of surgery-enhancing advantages such as better depth perception and the use of digital color flters.Such features enhance visualization and improve vitreous removal during surgery [25].
Tere are some limitations of the endoscopic vitrectomy system, like the lack of stereopsis and the inability to perform bimanual surgery.Tat is because the surgeon is viewing a screen rather than through two microscope eyepieces.Terefore, there is no stereopsis possible.Non-stereoscopic visual cues are needed for distance perception through shadow and changes in object size (degree of magnifcation) [26].Furthermore, the intraocular instruments are difcult to orient under the endoscopic view.Te operator should look back to microscope to confrm doubtful positions.Te way we had combined the endoscopy with 3D heads-up viewing system allowed integrating both the endoscopic image and the wide-angle view image on one monitor screen.Te surgeon could thereby operate without the need to exchange the view from microscopy to the 3D monitor.Tis helped the surgeon operate more comfortably, efciently, and safely.
We also conducted a thorough literature search on reports that combined endoscopy with 3D heads-up viewing system.However, we found no relevant literature on this topic.Our present study is the frst of its kind in evaluating the performance of vitrectomy using endoscopy combined with a 3D heads-up viewing system in treating traumatic ocular injury.In the acute stage of open globe injuries, an early vitrectomy has risks of fuid leakage from the wound, intraoperative bleeding, and poor visualization of the vitreous cavity.Our results demonstrated that small gauge vitrectomy assisted by endoscopy combined with a 3D heads-up viewing system was less invasive and well visualized, minimizing risks of early intervention.
Our present study has some weaknesses like its retrospective nature, no control group, and variability of eye conditions following trauma and surgical steps.Another limitation of the study is its small sample size.Larger clinical studies are needed to confrm efects of this new approach.

Conclusion
In modern microincision vitreoretinal surgery, the endoscope and 3D heads-up viewing system are both valuable tools.We here have described a case series of ocular trauma treated with vitrectomy based on endoscopy combined with a 3D heads-up viewing system.Teir anatomic outcomes were good.Tis system allowed early evaluation and intervention in traumatic ocular injury even with an opaque cornea.It provided a precise and complete vitreous clearance during vitrectomy, reducing the risk of anterior proliferation that could result in severe PVR, hypotony, and retinal redetachment.

Figure 1 :
Figure1: Te intraoperative image from patient no. 5 (a 45-year-old man sufering from chronic trauma with corneal scar and pupil synechia).Two images on the monitor were merged horizontally into polarized 3D glasses to create 3-dimensional image (a).Both the endoscopic image and the wide-angle view image were integrated on one monitor screen, which make the surgeon know the direction more clearly when performing endoscopic surgery.Retinal detachment with PVR changes was noted by endoscopic image (b).Te retina was reattached and laser photocoagulation was applied.3D endoscope visualization system ofers a good vision in an air-flled eye (c).

Table 1 :
Summary of patient characteristics and surgical procedures.

Table 3 :
Comparison of fnal visual acuity distributions between OTS prediction and our series.

Table 4 :
Comparison of fnal visual acuity between OTS prediction and our series.